The invention more particularly concerns the family of apparatuses that deliver to the core pulses of high energy (i.e., pulses notably exceeding the energy provided for simple stimulation) to try to put an end to a tachyarrhythmia. These devices are called “implantable defibrillators” or “implantable cardiovertors,” it being understood that the invention also covers implantable defibrillators/cardiovertors or defibrillators/cardiovertors/stimulators.
“Implantable defibrillator” or “implantable cardiovertor” devices have two principal parts—a pulse generator, and a probe or a system of probes. The pulse generator monitors cardiac activity and generates high energy pulses when the heart presents a ventricular arrhythmia that is deemed susceptible to being treated. When the high energy is comprised between approximately 0.1 and 10 J, the therapy is referred to as “cardioversion” and the electric shock is called “cardioversion shock.” When the high energy is greater than approximately than 10 J, the therapy is called defibrillation and the electric shock is called “defibrillation shock.” The pulse generator is connected to one or more probes comprising electrodes whose role is to distribute this energy to the core in a suitable way.
The present invention relates to the particular case where the generator is connected to a “mono-body” probe, that is a single probe carrying the various electrodes making it possible to deliver shocks of defibrillation or cardioversion. The shock electrodes appear as windings of wire supported by a distal tubular extremity of the probe and are intended to come into contact with cardiac tissues at the place where the cardioversion or defibrillation energy must be applied. The windings are connected to a conducting wire traversing the length of the probe.
Mono-body probes generally comprise two shock electrodes: a first electrode, known as “supraventricular,” which will be positioned in the high vena cava to apply the shock to the atrium; and a second electrode, a ventricular one, which will be located more closely to the distal extremity of the probe.
The mono-body probes are generally of the “isodiameter” type, i.e., they have the same diameter over the entire length of the distal part intended to be implanted in the venous network. This facilitates implantation, as well as any later explantation. This means that the external surface of the windings forming the shock electrodes is flush with the external surface of the probe, so as not to present any change in diameter along the implanted length of the probe.
The manufacturing of these mono-body probes is relatively delicate, taking into account the presence of the windings, the requirements for continuity of probe diameter, and the need for carrying the electric connection inside the body of the probe with the electrical conductor allowing delivery of the shock energy.
The technique employed until now to manufacture these probes consists of taking a plurality of tubular sections of encasable sheath, one after another, setting up the windings, and electrically connecting them progressively to their internal conductor at the various sections of the tube of the probe. This structure, which makes it possible to answer the specific constraints associated with manufacturing these probes, has, however, the disadvantage of creating zones and/or electric weaknesses at the places where the various sections are connected, in particular short-circuits on the high voltage conductor supplying the shock energy. However, in practice, it has been noted that the ruptures of the insulated tube support often occur at the places of the connections between the various sections of sheath, because of the zones of weakness locally created at the place of these connections. Moreover, this structure of encased sections implies a relatively complex and long manufacturing process, in particular because of the need for sticking the successive sections together. U.S. Pat. No. 6,374,142 and PCT Application No. WO-A-02/087689 describe such mono-body isodiameter probes produced starting from encased successive sections of sheath.